A Practical Cooperative Multicell MIMO-OFDMA Network Based on Rank Coordination

TL;DR

This paper introduces a practical, low-overhead cooperative MIMO-OFDMA scheme that optimizes transmission ranks and user scheduling to significantly improve cell edge performance in wireless networks.

Contribution

It proposes a novel distributed coordination method based on interference pricing and rank recommendations, enhancing cell edge performance with minimal feedback and robustness.

Findings

Achieves 20% cell edge performance gain over LTE-A

Operates with low feedback and backhaul overhead

Robust to channel measurement errors

Abstract

An important challenge of wireless networks is to boost the cell edge performance and enable multi-stream transmissions to cell edge users. Interference mitigation techniques relying on multiple antennas and coordination among cells are nowadays heavily studied in the literature. Typical strategies in OFDMA networks include coordinated scheduling, beamforming and power control. In this paper, we propose a novel and practical type of coordination for OFDMA downlink networks relying on multiple antennas at the transmitter and the receiver. The transmission ranks, i.e.\ the number of transmitted streams, and the user scheduling in all cells are jointly optimized in order to maximize a network utility function accounting for fairness among users. A distributed coordinated scheduler motivated by an interference pricing mechanism and relying on a master-slave architecture is introduced. The proposed scheme is operated based on the user report of a recommended rank for the interfering cells accounting for the receiver interference suppression capability. It incurs a very low feedback and backhaul overhead and enables efficient link adaptation. It is moreover robust to channel measurement errors and applicable to both open-loop and closed-loop MIMO operations. A 20% cell edge performance gain over uncoordinated LTE-A system is shown through system level simulations.